Heat exchanger



Spt. 23, 1952 Film1A Jan. 17, 1948 s. c. COLLINS 2,611,586

yHEAT EXCHANGER 3 "Sheets-Sheet 1 Sept- 23, 1952 s. c. coLLlNs 2,611,586

HEAT EXCHANGER Filed Jan. 17, 1948 3 Sheets-Sheet 2 Ef'g- 45 39 44 24A 25A 26A lv n...

Sept. 23, 1952 s. c. COLLINS 2,611,586

1 HEAT EXCHANGER Filed Jan. 17, 1948 5 Sheets-Sheet 3 la'g. 9. 59

A Ez/vento?? Samuel C. C'o ZZ nat Patented Sept. 23, 1952 nmmEXcHANGER Smuel' Cornette ClIiils,

Watrtowm Masas. ,ase

My invention relates to heatziexcl'iangers;anda more.-haiticularlmbut.notexelusiveln;fto;heatzeL changers; off astypefwhch siWel-Ladapted; fer,- use; in.V apparatus; for;v the; separation-,1of"gEt-Ses;x for: @Xi-f amplethe separation;cfaairntc;itseiirincrll QOH;- 5 stituents; Y

Inl anparatusfor; separating air into; itsf censtituents; it3 isv necessary torreducegfthe. temperaf ture; ofthe;v enteringlgair: and: to;` remore: from; it; carbon.; dioxide andv-,waters-vapor; and;it@isvlrnnore'Y 10 tant..to.,saveiasamuch of:themefrieeratonfaseDose#f sible; These?endszmayfbe;ac complishedbmusinez; reversing; heat exchangersi.- In suchafkheamexchangea, atzf ai given moment.=, airrfwill; Aenten-ther: system-1jthroughf,y one courseewhile.: the: nit-meen..V 15 produetfleaves;` through .anethemthmds-:move ing;imconnterotwrelation; Periodicallysthefzine ovn'oflfair'wiib bswitched-.ittheeourse through which; nitrogen been; leaving, and.`4 the,=-out iiowfof .ynitrogenwillehe switched to: the` course;` 20 throughfzwhich. arzfhasiheerrentering; l Carbon dii-f oxide and Waterfvapor irnthetenteringfair willi-be. frozenaontA andi` depositedi' in; the heat: exchangercourses:While:these are@ beingt traversed'- by theyV entering;air.:Y Thenitrogen;..omits Wayfont,isulcn-A 25 limesgthegcarbon.:dioxidezsnowfandice,; ande' care ries; theseimpurities outofzftheasystem; In;V somei heatiexchangers,,tofincreasethecoolngofthe enz-fi tering: ain, a,l third .i eQurse,fmayihevpmvided; and'.1

the oxyeem prnductris; passedfi throughf this fthirdiv 3o course-omits WayA storage.VV or; use. t'siiowris notzshifeted; periodically; an'dis; desirably; ata'llv times-, inzcounteruwireiation to, the: entering *ain Such'. heat.V` exchangers--whether:l of?A the two course: onthreez-coursetypemayfas.sumewraricus` 35 forms, andfit is; a purpose-ici?my*y inventibnztoa provide an; improved; heat` exchanger!` ,off each;- type. Among the.4 numerousv varieties: off. heat; ext-V changers are thosein Whiehitlie mth/ing stream'sz; 4o

of. substances between. which heat. exchange; i'szto: be etfectedhavej heattransmissioneiectedflarge-- lyfby conductionthrough:substantialfdistancesxbyf the' metal'A forming; the. walls` ot ther passages;All

:rather than by a direct transmission fromI one 45,V

sid'e .to theoter oimetallwalls Whchlierbetween andi' separate. the. flowing streams of; substances;

` betweenwhichheattransfeniato:he,1e1ected.. For:

exampie; two. substances atfdiferent temgerzar-itures maybe; admitted toadjacent passages-l and; 5.0

t1ie` streams have. much moreKY extensye contact, 5-5

prior constructibnsrare( nec@SSary.` Withheat.excilangers,v Whichimay, be maden@pt seriesv ofl separators welded;- brazedinonspldertdtoi metal,L plates in sucht amannen that; a number; ofjjthm; uidffstreams may passtinhelsame d. iretiomttf` is, necessaryc to space, the; supply: andLA discharge' connections .for eacnudlas far; apart asgiS: Pr't' through thapl'atesfrom one end'gto thezother; site is; also.y possible; L haver found. transversely# slottiheetherpassaee; wallsinotgonly to, reducedtof a very marked degree, the heat"transferv longitu-e dinally through .thelxietaL0 f, th,eY walls; lLgu t, alson` tofsetun withilttenassages;seri' sotsuccessive.

mainly in its layers indirect contact;with the; plates,vr through o,ft-repeated;v changes in; .velocityyV undergoes. repeatedpmixine oiiits constituntf P9P-- tions,..and,betw.een.eacnimperfpratenassaee:walt portion;v andithe next there is @LU-Least: a, negrtial: remixne of the flilid,..so thatlthe heatinaV Qficer tain, nortionsfthereofj (orconyerselg the cooling);

whiIe, other portions remain with.,y littlel change in,temperaturais..avoided;

It is an object of'my inventionxte. @renuevan/s improved heat exchanger. It is another? atleetVw off myv invention to provide* an imprevedeheaitfexchanger formed; ot thin pl'atesections and' sepa;

between entering streams of air and leaning-;y streameoffnitrogenecwingerelatiuet o1. an A appara.- tusi fm:- separating;- ain-infilo;l its., constituentst Lt" l: stur another-obietsieimiinientenzte otidefan improved heat exchangerihzving not; tcpuifseafor the nuwe-*preferably in;y counterfiow; relationship-of streamsoifair underpresen-1re,andntmegen.; but' also haw/ingr in amodil. arrangement, a ,thirdpassag,9%` softhat a,,l'eatiiigstream otiexxggen.

vention toprovideaniinm'oved:iheatiexchanger@l l A ani-mprevecl-v construction-.forme transfercf ideati;Uv

3 may ow in heat exchange relation to the other streams. It is still another object of my invention to provide an improved form of heat exchanger in which heat loss will be minimized and in which the maximum possible amount of heat will be transferred through the walls of the heat exchanger from one substance to another, with a minimumV loss of heat through; the material of the heat exchanger from the hot end to the cold end of the latter. Still a further object of my invention is to provide an improved heat exchanger having an improved means for eiecting repeated turbulences in the flowing streams, with the result that there shall not be a mere stratied heating and cooling of the substances in heat exchange relationship. Still another `object of my invention is to provide an improved heat exchanger structure. The chief criterion of a superior heat exchanger is its elciency, which is based upon the quantity of heat transferred per degree difference in temperaturebetween the two counterstreams. Yet a further object of my invention isv to provide'an improved construction of heat exchanger for the interchange of heat between three substances. It is still another object ofmy .invention to provide an improved heat exchanger which shall transfer 'a maximum possible quantity of heat per degree of difference in temperature between the counterstreams of fluid, which shall insure the maximum emciency' of heat transfer between its walls and the fluids owing in contact with lsaid walls by insuring maximum possible temperature diiierences between the streams and walls at all points by causing. the warmer portions of such streams repeatedly to be remixed with the cooler portions, orvice versa, so that the flowing streams will have their portions in contact with the heat transfer walls continually rebrought to a condition of maximum possible temperature difference with respect to said walls; .and in which` heat leakage by conduction through the wallsof `the exchanger .between the hot and cold ends thereof shall be kept at a minimum with a'v resultant improvedy utilization of the temperature difference available to effect heattransfer. Other objects and advantages of the invention willhereinafter more fully appear. p

In the accompanying drawings, in which one formand several modifications' which my invention may assume in practice have been vshown for purposes of illustration, t y

Y Fig. 1 is an elevational view of a vertically disposed. heat .exchanger and with parts broken away, 'showing an illustrative embodiment of the invention in which provision is made forheat ex'- change between two substances. K Fig. 2 is another .elevational view of the structurewhich is shown in Fig. 1, turned through 90 and withparts broken a'vvay to show ,details of interior construction. l

ig. 3 is a view otone. end `*lof the exchanger shown in Figs. 1l and 2, 'with parts broken out, and'particularly showing manifold arrangements. Fig. 4 is a horizontal-'transverse section on the plane of the line 4-'/i of Fig. 1 on a larger scale,

while Fig. 5 is a similarr horizontal transverse sectional viewon the plane of the line E-Eof Fig. l. Fig. 6 is a=fragment`ary sectionalview onthe plane o'f'the line ii---l of'Fig. 4.` Y

` Fig. '7 is an enlarged fragmentary sectional View on the plane ofthe-line l- 'ofn Fig. 1. t'

{Figi} is an'enlargedhoriaontalsectional view,I on a planeparallel to the plane of the section 4 line 1-1, showing a modified form of construction, the modication inhering particularly in the manner of forming partitions between the flow passages.

Fig. 9 is a view generally similar to Fig. 3, showing one arrangement for the inclusion of a third iiuid in .the heat exchanger.

Fig. l0 is lan enlarged `fragmentary section showing a detail of construction of the modification of Fig. 9.

Fig. 11 is a view of another modification in which there are diierent arrangements for heat transfer with respect to a third iiuid.

Fig. 12 is an enlarged fragmentary sectional view of the construction shown in Fig. 11, the section being taken approximately on the plane of the line l2-l2 of Fig. 13.

Fig. 13 is a sectional view on the plane of the line I3--l3 0f Fig. l1.

Y long, andspaced from-one another lengthwisexof Fig. 14 is a detail showing another modified form of construction.

Fig. 15- is an enlarged fragmentary view looking at the facevof one of the perforated sheets, show" ing still another modified form of construction.

Fig. 16 is a sectional view taken on the plane ofv the line Iii-I6 of Fig. 15.

Referring to the drawings, and iirst to Figs. l

to 7 thereof, it will be' observed that I have shownv a large number of relatively long, narrow, perforated sheets 20, each provided at '2| with series of parallel transverse openings. desirably be of copper or other material which is a good conductor of heat. In one physical embodiment of the invention, which will-of course be understood to vbe described merely for purposes of illustration, and not to implyuany limitation, the perforated sheets will be on the order of six feet long, six inches wide, from. ten to twenty thousandths of an inch thick-.0125 is a-desirable. value. l For the. other dimensions enumerated, I have rows of six alinedA perforations or slotsll each rperhaps one-sixteenth of animen-- wide and some three-eighths and others one inch the sheets by distances on the order of --ther widths or a smallxmultiple thereof; andthe sheets may. be *arranged about .020" Japart.'v 'The' func-v tion of the slots. is to reduceheat conduction longitudinally of the sheets and to increase the heat transfer coeiiicient as later described. Figs. l to 'l show the slots 2l in six rows, from points near one end of the sheets to points near the other` end; andA the rows are separated .byrelatively narrow imperforate portions of the sheets,`

and .there are relatively narrow imperforate edge portions ateach .side edge of .each sheet. The

several rows of slots are indicated for easy ref-V erence as 22, 23, 2li, 25, 26 and '21. Between `therst slot ineachy row and theextreme opposite slot, the rows of `slotsare continuous except at points whereclamping bolts are to beV` provided,-

suchV clamping bolts,` 28, vpassing as shown in Fig.

7 through openings 29 just enough larger than the boltsto provide comfortable clearance. p

Each of the plates y?(l'in'addit ion to the numerous relatively long lnarrow parallel slots through'it, is traversedby openings or windows through whichV uid may flow from appropriate headers, shortly to be described, into the spacesv between the plates. These openingsare desig-v nated by the same reference charactersfasthe slots with which theyare respectively. associated, the openings at one end of each row beingdesig- Y nated by thevsuifix A and those at the V other end of each row by the'suiixB. There are thus in' These sheets may l 53,61 ILSG each plate, openingsor windows 22A,:23A,. 24A.. 25A,..i26AandZ'IAatfioneend 'of4 thestrip, 'andi openings 22B, 23B, 2413,v 25131263 and Y21]?1at the other end oi-the strip, inthe constructionA illustrated.

yBetween each pair yof plates there extend: a. series of longitudinally arranged wires or other partition elements. thesebeing' 0f` such` a dimen- 29.1ie between the wires ory partitions 32 and33.

Itis unnecessary to enumerate the. relation 'of vthe other series of. openings and. slots 'to 'the other pairsoi wires or' partitions in detail, it being.

enough to say that between wires or partitions 33 and 34 the slots 2'4 and associated Aopenings-are disposed, between the wires or partitions 34 and 3-5f'the' slots 25 andV associated openings 'are dis'`- posed, .between the wires. or partitions 35 and 3b".V

theslotsZB and associated openings are. disposed,

and-the slots21 and associated openings are disvii posed between the .wires or: partitions 36 and 3i f The wiresimay,as shown in Fig. 7, not all be arranged with their axes in a common plane, but may be slightly staggered laterally relative to each'xother so as toprovide'a certain degree of iiexibility. The wires may be soldered in place. or brazed in place, in any suitable manner, and if desiredfthe entire pack" of plates. and wires may bedipped when desirable in a suitablevbath of' molten metal,` such as solder, to. effect the sealing ofthe walls of the many passages. The opposite `ends of the spaces between each pair of longitudinally extending wires orI partitions is closed as by shortl elements. E soldered or brazed'in position. so as'to sealithe end of each passage formed between thevarious` plates.. Next to and outside ofthe most widely separated plates. 2l), there are relatively heavy, rigid,.outside plates `3l and 38. Each orthese platesis shown as having openings or windows init, later referred to by 'reference characters. overlying the openings 22A Ito 21A and.22B to 21B. They might, however, be windowed only in the same way their associated headers are windowed, if desired.

- To conduct iiud to the passages formed by the plates, various header arrangements may be employed. For. example. end headers similar to those shown. lnmy application Serial No. 3'21'7 filed January` 20, 1948, might be employed by omitting end seals and xing headers to the ends of the .plate stack. For purposes of illustration in: this case, however, I have shown header elements bolted to the opposite ends of the outside plate. 3l and other header elements'. bolted to the outside plate 38. These may be considered as being.- in top 'and bottom pairs, the top pairs numbered`39 and 4B and the bottom pairs numbered 4i and 42. The top header 39 has, asshown, an

end connection 44, say for the admissionvof one.

of the substances whose heat content is to be changed, and it contains a chamber and has a plane wall 45 in which there are formed arelatively narrow opening 41 and two wider openings 48 and 49; These three openingsV communicate with the openings imi,r 24Avand 26A in the 'series' oflperiorated plates: 2ll,lhavingzsuch eoinm1J.'nirtel f tion through'correspondingopenings 41214325 and 49 formedV in the outside-platen. yIt wilttlrus be;Tv

evident that. the uid enteringzthe chamberi 45 may pass through theopeningsz 2A, za'andszazs infthefperforated plates 2li-:andthe openingsrin the outside plate 348 all the wayto. the walker.. the-headerA 4U- which 'is' imperforate. in linexwitir.

enter all of the longitudinal passages.; bounded.

laterally by the wires Sor partition elements 30,132; 33, '34; and 35, 38.

54! and 55' formed in the outside plate 38,. the openings 23A, '25Ak and. 27A inthe adjacent one of the plates 20 and withall the other;v open ings bearingv lcorrespondingnumbers Vall the way-r to 'fthe'wall 4G, which .is imperiorate inline with.

the. openings 53", 54 and 55..

At the otherv end of the lheat* exchanger,- as; shown in Fig, 5, the header 4| .is provided withvan ingress (ingress, if 431s adischarge header): connection 59, andra chamber 60, which, through openings 6l., 62 and 63, and corresponding.op'en:-V ings 6l,. 62' and 631in theoutside plate 31 oomsmunicates with the openingsv 23B,` 25B and .21B in the yadjacent perforated plate-f23 and kin all of the other plates 20.y The wall of the header42 is imperfora'te inline 'with'v the series 23B, 25B and 21B.'

a chamber 66 which communicates` through open-y ingsV 61., 68 and 63, and corresponding openings 6T', 68 and 63. in the outside plate38, .with thel slots 22B,.24B and 26B inthe adjacent perforated plate 2.0, and withthe corresponding. slotsfin all:

of the other plates lying between the outsideplates. "Il'iewall of the headery 4| is imperf'orat'e in its 'portions which are in line with the vseries-'oi openings 22B, 24B and 26B. Thus it will be api 2' parent that one fluid entering through the'con-` nection 44 will have access toall of theopenings 22A, 24A.and 26A, and at the other'end "oi'Lther heat exchanger the openings 22B, 24B and26B communicate with-the header 42, so th'at'there will be flow in three series of parallel passages from the top header 39 to the bottom header 42; and, correspondingly, there will be counterilow from the bottom header 4I tothe rtop header 40.1 at the other end of the exchanger.

When the heat exchanger isk to be-usedga's a: reversing heat exchanger, the :headers 39 andy 40 will alternativelyserve as means :for-the ad:- missio'n of one iiuid, whiler the headers 4l andi 42 will serve alternatively as means for the .admission of the other fluid, and vthere will be'alAi ternatively flow of one fluid in atr 39'and out! at 42 and of the other in at 4I and out at 40; and flow of the first fluid .in at 40 and out' at- 4| and of the other in at l2y 'and outat 39.

By reason of the slots 22, 23, etc., whichfgreatly reduce 'the freedom of heat Itransfer lengthwise `of the vplates 2U, there 'will be very little:heat"A loss lengthwise of these plates through the `metal ofthe heat exchanger, but the heatabsorbedf by l the .portions of these plates surrounding' one- Series 0f openings will be conducted very esac-- tively through the metal of the plates.v` to the metal surrounding the adjacent series offp'erforations, or. pairof series, as the 'case maybe As the fluids 'flow .longitudinally betweenthe Theftop header 40. hasiif 331:. issafsupplyfheader, a connection 5t iorthejegress.y oi'A one of the; substances which undergoes:heat: exchange,. and contains a .chamber 5.2 having,` openings53, 54 and 55,' connected by openings 532i kThe header 42has (assuming the-headerbe a supply header) a delivery connectionitand plates, each time they pass between imperforate4 wally portions, there is-a 'heat 4transfer between the `opposite'sides of vthe uid streams and the wall-portions. Each time the iluid passes out from between 'a pairof opposed'wall portions to' a space between-slots,` there will be an ex' p'ansion, and a marked turbulence, anda remixing of the fluids which had had their outermost layers, so to speak, undergo a slight change in temperature. i

,'In,-Fig. 8,*a modification of the arrangementsv for forming the lateral walls of the fluid conducting passages is shown. In this view, instead ofusing the' roundWire-like partition elements 3 0, 3.l,=fetc., material rectangular 'in cross `section fisindieated `at 1I, and when the heatexchanger is'assembled, wire solder 'I2 is placed alongside each partition member and "suitably held'there .soithat when the bank of exchanger plates' andrpartition members have been fully assembled, they may be heated and the--solder melted and caused to ow by capillary action through the'joints between plate and partition elements and effect sealing.

In. the Vuse of the apparatus so far described in an'air separation plant, itA will be understood that'there will be provided appropriate valve mechanisms 'which' will permit switching of the nitrogen and air between the sets of passages, but that the nitrogen will always now' longitudinally of the heat exchanger in one direction whilethe air will always flow in' the other di' rection, irrespective of which passage series conducts either fluid. Ordinarily, the air will enter at Vthe bottomv and thev nitrogen at the top of the courses through which they dow.

' Aspreviously indicated, in the provision of a heat exchanger `for use in the separation of air intoits principal constituents, it may be desirable-to'have the oxygen product, as well as the nitrogen product, pass through the heat exchanger. It is desirable that the passages for theentering air vand leaving nitrogen shall be of relativelyf equal cumulative cross sectional areas. The oxygen conduits, however, need not be so large, and particularly if oxygen under substantial'pressure isjto be the product the cross sec.v tional area of the oxygenV conducting passages may bemade relatively small in comparison with the passages for the iiow of nitrogen and of" entering air.

In Figs. 9 and 10, and in Figs. 1112 and 13, two different modiiications of the invention are illustrated, theseV showing three-pass heat exchangers, and the oxygen is, in each case, conducted in counterow relation to the entering air.: Thus, if Yit be assumed that at one time the nitrogen enters through the header 39 and leaves by way of the header 42, and that at other times the nitrogen enters by way of the header 40 and leaves by way of the header 4|, it would be desirable to have the oxygen enter through header means 'at the same end of the exchanger asheaders 39 and 40. at the same end as the nitrogen, and leave at the same end as the headers 4| and 42, i. e. at the same end as the nitrogen. In the construction shown in Figs. 9 and 10, there are provided pairs of horizontal headers 8l, v8l and 82, 82 at the opposite ends ofthe plate bank, the pair oi headers 8i at the same end as the headers 39 and 40, and the headers 82 at the same end of the heat exchanger as the headers 4i and 42. These head-1 ers have suitably secured toithem and in communication` with their interiors, which may be,

regarded forpurposeslxof illustration as cylin-IA drical, parallel series of vertical tubes 83, these tubes being of suitable crosssection to provide for the necessary ilow volume, and being brazed. soldered, or otherwise suitably secured to the side edges of ,the plate banks, as shown in Fig. 10 to;v provide for efficient heat transfer; I Oxygen product may be' delivered vto vthe` headers 8| bya conduit l85,-a T86, and. branch connections,

8l leading to the headers 8l, and, having passed through the longitudinally extending tubes 83, will enter' the Ahollow .headers j 82 v'and' be` kdelivered from the latter todischarge conduits 88, which may obviously be connected together, .if desired. Thus it willbe. apparent that theox-` ygen conducting, pass or the heat exchanger in the form of aseries of tubes, in good heatexchange relation to the plate banks, and headers with which the 'tubes communicate, may be arranged on the-outsiderof the plate:bank` heat exchanger first described. It is also possible,

tudnally extending'tubes each :side kby side as at 9i arranged between andy soldered or brazed to the edges ofthe two banks ofplatesas shown in Figs. 11, l2 and 13, there may be .effected the conducting of oxygen in heat .exchange relation to the plate-and-separator-constituted 'fluid conducting means. i o

In Fig. 14, there is shown an arrangement' of the slotted plates 24.1 in which, instead of having separateiwire-or partition elements, there" are longitudinally extending beads Sii-formed oneach plate, and. when the plates are assembled, wire soldenasiat 96, is-laid in each bead so that upon the heating of the assembled unitthe solder may effect a seal along the outer surface of one bead andthe contacting inner surface of: the next adjacent bead. Thereby, a readily and-effectively sealed arrangement willbe produced and the structure .will not have to have a loty of separator wires orpartitionelements care-.-

fully laid with respect to each pair of plates.

- It is desirable that there shall not have to be toolarge a pressure diierential between the opposite ends oi the heat exchangers. Turbulence creation maybe accomplished primarily by mere velocity changes, or in part also by'partial bailling of the owing streams of fluids. When the edges of the slots 2l are relatively sharp,"there is somev baiiling action, with excellent turbulence creation but also some increase in now resistance. In

Figs. l5 and 16, the plates 20".are twice rolled'-. though they could be otherwise formed-being' perforated in one Aset of rolls and being then fed through another'set to form the metal M between the slots more or less oval in cross section, so as to causethe turbulence to be produced more by the changeV in velocity, as it were, and to diminish corner or edge action of the imperforate portions-the bars so to speak-on the'layers or streams of fluid.

From .the foregoing description, it will berapparent, that I have provided an improved heat exchanger; that Ihave provided an improved:

heat exchanger of the two course and also of the g three course type; and that the heat ,ex-g

changer willbelof g1g" l A telciency in that there will be, due 't"the`fa t"tl`i`t"tlie length of the heat loss by direct conductionlongitudinally"of the plates,,such.,ccnd1lt91.keine Llargely Pfevented by the employment of'the slots. It will further be observed thatnbecause of themar'ly moving ribbon-like streams "of air or gas, the maximum rate of heatitransfer from platesto ence between the fluid temperature and the plate temperature will always be maintained at a substantial maximum. The structure is comparatively easily built, is strong, is not likely to be damaged even by the use of considerable pressures, may readily be sealed in a manner to prevent leakage, and, through the multiplicity of channels provided, can handle relatively large quantities of fluid although not oi' great overall transverse dimension.

It will of course be understood that the dimensions given are but illustrative and that while a construction, of a length of several feet and slotted and of the illustrative thicknesses of material described will bevery eiective for a heat exchanger of a given capacity, very wide variations in thickness, size and number of plates, slot width and breadth, number of rows of slots, etc'. are within the purview of my invention.

While there are in this application specifically described two forms and modications of each which my invention may assume in practice, it will be understood that these forms and modiiications are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

l. In a heat exchanger, in combination, sets of thin elongated plates stacked side-by-side each having throughout the greater portion of its length a plurality of rows of relatively long narrow slots, means cooperating with said plates to space the same and to coact with the same to form longitudinally extending passages transverse of the slots and substantially parallel with said rows, the slots providing communication transverse ofthe plates and from one part of a passage to another part of a passage, a first header adjacent one end of the stacked plates and having a wall with spaced openings communicating with alternate passages, a second header adjacent the same end of the stack and,

having a wall with spaced openings communicating with passages intermediate the alternate passages, a third header adjacent the opposite end of the stacked plates and having a wall with spaced openings communicating with said intermediate passages, afourth header at the same end as the third-named header and having a wall with spaced openings communicating with the alternate passages, whereby a fluid may iiow through the first-named header and the fourthnamed header and pass through the alternate passages, and still another fluid may flow through the second-named header and the third-named header and pass through the intermediate passages, and tubular iiow conduits extending longitudinally between pairs of said sets of plates ln- .qn aanname' am,

10 h`terrnediate pairsof saidcqactinameansertan ai etscfplat' 'peine securedtgthegd- 'cnlduisprovidins.passage for atlid uid,

"En 'a'heat exchanger', `inl combinatie ,of-thin lans'ated` plates. arranged 'sdeUv toy for'mjafstacl' and eachhaving throughout, he greater porti'onnf Lits] rlength plurality' Oi ,IOWS 'ofrlativly'long narrdv'v's1ots,and. havingl transverseA of the plates and from one part of a passage to another part of a passage, a rst header adjacent one end of the stacked plates on one side of the stack and having a wall with spaced openings aligned with alternate openings in said plates and thus communicating with alternate passages, a second header adjacent the same end of the stack and having a wall with spaced openings communicating with openings in the plates intermediate the alternate open= ings and thus communicating with passages intermediate the alternate passages, a third header adjacent the opposite end of the stacked plates and having a wall with spaced openings aligned with openings in the plates to communicate the spaced openings of the header with said intermediate passages, a fourth header at the same end as the third-named header and having a wall with spaced openings aligned with openings in the plates to communicate the fourth-named header with the alternate passages, whereby a fluid may ow through the first-named header and the fourth-named header and pass through the alternate passages, and still another fluid may flow through the second-named header and the third-named header and pass through the intermediate passages, and tubular flow conduits extending longitudinally between pairs of said sets of plates intermediate pairs of said coacting means, certain of said sets of plates being secured to the adjacent sides of said tubular conduits, said tubular conduits providing passage for a third fluid.

3. In a heat exchanger, a plurality of relatively thin plates arranged side-by-side and heavier outside plates, and partition elements cooperating with said plates to form a plurality of long, relatively wide and relatively shallow passages separated from each other at their edges by said partition elements, each of said relatively lthin plates having a series oi long narrow slots formed through it and arranged in rows, the length of said slots being nearly equal to the width of said passages, all of said plates having larger openings near both ends for conducting uid with respect to said passages and each of said thin plates having one said intermediate passages through other alternate ones of said larger openings, and a fourth header at the same end as the third-named header and having a wall with spaced openings communicating with the alternate passages through larger openings intermediate said other alternate larger openings, whereby a iiuid may flow through the first-named header and the fourth-named header and pass through the alternate passages, and stillanother fluid may flow through the second-named header and the thirdnamed header and pass through the intermediate passages.

SAMUEL CORNETTE COLLINS.

12 REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Date Number Name 1,692,391 Stancliife Nov. 20, 1928 1,734,274 Schubart Nov. 5, 1929 2,439,208 Gloyer Apr. 6, 1948 FOREIGN PATENTS Number Country Date 868,064 France Dee. 15, 1941 

